Erse Super Q 17mh 16awg mod to SDA-2B TL's

audiocr381ve

I thought it was worth opening another thread to share my experience with these inductors on my 2B TL's.

It's early...very early. I know. But here goes.

First off, I'm no professional. I don't have any measurement tools other than my ears. I try my best to follow instruction from those who have been generously sharing information.

Procedure

First thing I did was pull off the passive radiators. I clipped the cables going from the xover to the stock inductor. I kept the clipped cable that was terminated so I could do some comparisons as I tune the new inductors. I placed the new inductors in the right corner as far away as I could get them from everything else and placed them on some foam. I took some wire-nuts and connected the new inductors to the clipped (and stripped) cables from the xover. I then listened...

It was thin. Is there any bass at all? Maybe I'm just hearing things. So what I did next was reconnect the stock inductors and listened. There it was. The same bass that I'm used to. I played about a dozen familiar songs with the stock inductors to get a feel for what I'm listening to. I made sure to listen to songs that had a solid kick drum thud, upright bass, and familiar vocals to make sure I wasn't tuning for one and not the other. Scientific method? Well, that's as scientific as I get.

I took the new inductors and removed the black tape. I unwound the inductor 5 turns, then put the black tape back on and listened. It's getting better.

I repeated that process until I ended up at 15 turns. 15 turns must be the sweet spot because I've never heard such articulate and defined mid-bass coming out of these speakers. I could actually hear the runs the bass player was doing now! I put on the John Mayer concert DVD, Where The Light Is. When the John Mayer Trio performs, I always felt like I could hardly hear Pino Palidino, the bassist. Not this time. I could not only hear his bass, but I could make out the tone of his bass which is something I was able to do on other systems, but now with the sweet sound of the SDA's. Really cool.

Again, I know it's early, but so far so AWESOME lol. I'm leaving the inductors at 15 turns for the next week and then I'm going to reevaluate them. As far as I'm concerned, this is a must as far as mods go. It's fun to tune the bass to your liking. OldmanSRS was right in that the more turns you go, the more upper mid-bass you get, which is the bass I like to hear.

OldmanSRS

That's good news. It's amazing how integrated the bass and midbass become when the inductance value is achieved that provides the lowest bass and just enough bass above 100 to 150 hz to warm the sound without the excessive tubbyness (I had with the stock inductor).

I have gone back and forth between the stock inductor and the Erse to re-confirm how the tonal quality is so much more natural and the lowest bass comes through your skin acurately and well controlled.

inspiredsports

So can we assume the 15 turns unwound from the core brought the Erse 17mH component down to the Polk specified 16mH value?

Aw heck, I have a good dialogue going with Erse on my own project so I just emailed them the following:

##################################################
You guys [Erse] are fantastic. I'm so impressed with your lightning-fast responses.

I am posting heavily in threads in the PolkAudio.com forum where Erse now has a large following as many of us are updating our vintage SDA inductors.

As you know, I purchased 2 each 8mH to run in series to hit the Polk specified 16mH value on the nose, but many in the group are buying 17mH 16 gauge Super Q's and unwinding them.

Since I already have the dialogue going, I figured I would ask the following on their behalf.

When these guys modify the 17mH inductor "by ear", it seems unwinding 15 turns off of the steel laminate core makes them happy. Can you confirm that 15 turns unwound from the 17mH 16 gauge would approximate a value of 16mH ??

Sincerely,
Greg
##################################################

I'll post their response when I receive it.

audiocr381ve

inspiredsports wrote: »

So can we assume the 15 turns unwound from the core brought the Erse 17mH component down to the Polk specified 16mH value?

Aw heck, I have a good dialogue going with Erse on my own project so I just emailed them the following:

##################################################
You guys [Erse] are fantastic. I'm so impressed with your lightning-fast responses.

I am posting heavily in threads in the PolkAudio.com forum where Erse now has a large following as many of us are updating our vintage SDA inductors.

As you know, I purchased 2 each 8mH to run in series to hit the Polk specified 16mH value on the nose, but many in the group are buying 17mH 16 gauge Super Q's and unwinding them.

Since I already have the dialogue going, I figured I would ask the following on their behalf.

When these guys modify the 17mH inductor "by ear", it seems unwinding 15 turns off of the steel laminate core makes them happy. Can you confirm that 15 turns unwound from the 17mH 16 gauge would approximate a value of 16mH ??

Sincerely,
Greg
##################################################

I'll post their response when I receive it.

That's awesome man. Thanks for doing that. I hope you don't get a "they're crazy" response haha

audiocr381ve

OldmanSRS wrote: »

That's good news. It's amazing how integrated the bass and midbass become when the inductance value is achieved that provides the lowest bass and just enough bass above 100 to 150 hz to warm the sound without the excessive tubbyness (I had with the stock inductor).

I have gone back and forth between the stock inductor and the Erse to re-confirm how the tonal quality is so much more natural and the lowest bass comes through your skin acurately and well controlled.

Yes and thank you for all the help!

inspiredsports

audiocr381ve wrote: »

That's awesome man. Thanks for doing that. I hope you don't get a "they're crazy" response haha

I doubt if they will say that.

I know some here whom I have a great deal of respect for don't agree, but I've been giving this a lot of thought and am coming to the conclusion that fine-tuning an inductor may be a valid excercise.

I do feel that using instrumentation is the best answer, but lacking equipment, doing it by ear or turn-count may still be better than leaving the wrong value (17mH) in place.

Toolfan66

I like what Greg is doing with doing two in parallel but I am not to sure about this unwinding thing without the right measurement tools, But this is a hobby and having fun is what it is all about, and if it sounds good to you thats all that matters I just don't think I could do it cause I am way to anal..

Have fun!!!

OldmanSRS

A show of hands please.

Who thinks that the 16.8 mH inductor in the SRS1.2 was chosen solely with a calculator, installed, and the speaker sent to market?

Who thinks several value inductors were tested based on a calculation. The one that sounded the best was chosen, someone measured it and said "OK we need a bunch of 16.8 mH coils wound for manufacturing"

Toolfan66

Yeah I'm sure they just guessed at it "what was I thinking!!!" LOL!!!

inspiredsports

OldmanSRS wrote: »

A show of hands please.

Who thinks that the 16.8 mH inductor in the SRS1.2 was chosen solely with a calculator, installed, and the speaker sent to market?

Who thinks several value inductors were tested based on a calculation. The one that sounded the best was chosen, someone measured it and said "OK we need a bunch of 16.8 mH coils wound for manufacturing"

I'm listening and open minded, but if Erse had offered at 5% tolerence 16.8mH when you purchased, would you have fooled around with it?

OldmanSRS

inspiredsports wrote: »

So can we assume the 15 turns unwound from the core brought the Erse 17mH component down to the Polk specified 16mH value?

I doubt it. What we need to take into account with this mod we are changing several design factors on the speaker with one inductor.

1. The change from air core to laminate iron core brings with it a different set of performace parameters
2. Lower DCR better couples the SDA to the amp (follows the waveform more accurately), drives the SDA 100% more below 42 Hz, and almost 50% less above 200 Hz (see #3).
3. Identical inductance value air core and laminate iron core inductors have different electrical behavior with AC waveforms of varying frequency. The Erse inductors are better at attenuating the midbass than the OEM air core inductor. I though it was due to the lower DCR of the Erse so I added 2.5 Ohms of DCR in series with the Erse and XO output slope did not vary significantly, so it must be due to in part to permeability, hysteresis, etc.

What I'm saying is a 16 mH air core inductor with a 2.5 ohm DCR is not going to produce the same sound as a 16 mH iron core inductor with a 0.5 Ohm DCR in this XO. The voice of the speaker will change.

Therefore, tuning a slightly larger inductor by systematically removing turns, then evaluating the sound (and making measurements if desired) is a completely valid and logical process in engineering.

I don't understand the push back on this. Maybe it's just my years in R&D.....

OldmanSRS

inspiredsports wrote: »

I'm listening and open minded, but if Erse had offered at 5% tolerence 16.8mH when you purchased, would you have fooled around with it?

Depends. If it sounded awesome, like I expected it to, probably not. But it sounded bad, thin, lacking warmth, I mean really bad. I had to figure out was was going wrong with the circuit.

dorokusai

Oh by all means, your years of R&D make up for an absurd suggestion when it comes to unwinding inductors? Who cares? Your experience in the application you tried cannot be argued as it's your observation but suggesting that folks start (un)rolling their own is weird. Can you find that advice elsewhere? The tolerance % of an inductor is damn near inaudible at best and if you feel you can hear a change within a few DCR .000, that's awesome but for all intents and xover purposes for the masses....it doesn't matter in any way. I'm speaking in general terms here, in order to keep it simple. Yes, large DCR changes have an effect on sound, that's not in dispute here. I thnk you're caught up in a project and a placebo effect. You can keep the VOM measurements to yourself as again, ears are all I care about. DK has done enough great work in regards to all this and the lines are what they are....the changes are easy to see.

I applaud your efforts and the extra length at which you've went thru to experiment...hell, that's what this hobby is about. Xover upgrades are not rocket science and to further complicate goes against the original design in the first place. I prefer a loudspeaker to sound like it did when it was designed for the most part. A highly modified DQ10 is NOT a DQ10 anyore.

OldmanSRS

I knew I would get a response like that from someone here with > 23,000 posts.

Please everyone. Forget everything I said. Don't think outside the collective. Instead, go buy a pair of custom wound, $200 inductors, install them, burn them in for 400 hours and rest assured that you have the best sounding Polk's out there.

I'm too seasoned to get upset, have interesting things to play with, and I'm not the least bit interested in insulting others on forums.

WGDB

+1 to OldmanSRS - 23K posts is impressive. Whatever!!!! He's always talking down at people. Probably because he works at Polk. So the f&*F what..... I work for the Air Force ===== Ask me a question pertaining to the Air Force, or solicit my advice.... You'll get a polite response and I'll will go out of my to answer it without looking down my nose and talking rude!

Toolfan66

WGDB wrote: »

+1 to OldmanSRS - 23K posts is impressive. Whatever!!!! He's always talking down at people. Probably because he works at Polk. So the f&*F what..... I work for the Air Force ===== Ask me a question pertaining to the Air Force, or solicit my advice.... You'll get a polite response and I'll will go out of my to answer it without looking down my nose and talking rude!

Dude really!! this is all you have to add to this thread and fourm?? your better off keeping your mouth shut IMHO!!!

Mark your more then welcome to delete this post but this asshat is just attacking for the thrill of it..

inspiredsports

This is interesting stuff for sure.

The posts I've studied of DK's appear to support that lower DCR air cores of the same inductance value don't adversely affect bass response.

The posts I've studied of OldManSRS's seem to support that lower DCR iron core inductors may require a slight reduction in mH value.

I wish I had an inside connection to some commercial crossover designers who might have formulas to describe differences (if any) between air core and iron core inductors of the same mH value.

audiocr381ve

One thing is for damn sure. These speakers have never sounded better. The mids are just flat out warm and pleasing to listen to. I just want to turn it up!

Everything sounds phenomenal. Piano's sound more balanced, vocals are bigger and rounder but not congested.

OldmanSRS, these inductors don't require any burn in do they?

evhudsons

I didn't see any rudeness IMHO. This is a great thread. There are several of us trying to figure out the inductors, several are experimenting, and I'm watching, listening and waiting on the outcome. It's complicated even if it's not rocket science. You've all been given the green light and back pat by longtimers here to experiment and try new things, but if you are giving results mismatched to trials, I'm sure and would hope someone experienced would chime in. All in all I'm pretty darn impressed with everyones knowledge and inventiveness. The only problem I see in this forum is that people over react and think they are being insulted.
I was the smallest scrawniest guy in bootcamp, and I remember the biggest meanest guy crying, and I had to ask him, what did your recruiter tell you this was, petunia gardening? It's booootcamp. Anyway this isn't bootcamp but we aren't growing petunias either.
I'm looking forward to hearing about these inductors.
From what I've read is that inductors take a very long time to burn in, so is it possible that the turning of the coils might be too premature? Or are you just experimenting until burn in is dine, then adjusting to the best sound? I'm excited that both if you are having such a fast response. Inspiredsports I'm sure will have a good review too.

F1nut

It's amazing how integrated the bass and midbass become when the inductance value is achieved that provides the lowest bass and just enough bass above 100 to 150 hz to warm the sound without the excessive tubbyness (I had with the stock inductor).

Quality amplification and a set of Larry's rings does it better.

heiney9

F1nut wrote: »

Quality amplification and a set of Larry's rings does it better.

True dat, I have to add that a quality pair of speaker cables can do all this also

It's amazing how integrated the bass and midbass that provides the lowest bass and just enough bass above 100 to 150 hz to warm the sound without the excessive tubbyness

Exactly what happened when I switched cables.

H9

dorokusai

OldmanSRS wrote: »

I knew I would get a response like that from someone here with > 23,000 posts.

Please everyone. Forget everything I said. Don't think outside the collective. Instead, go buy a pair of custom wound, $200 inductors, install them, burn them in for 400 hours and rest assured that you have the best sounding Polk's out there.

I'm too seasoned to get upset, have interesting things to play with, and I'm not the least bit interested in insulting others on forums.

That wasn't even the point or suggestion. Sorry that conversation is scary....as far as I know, we're just talking here. It's hard to get inflection in typed speech you know. Oh well, do what you want.

If the results are positive, that's awesome and all that matters. I just happen to not agree wiuth your approach and recommendation/application. If my post count also scares you, it shouldn't since I'm no expert or an engineer, just a hobbyist. I guess I could go into my extensive lineage but who gives a ****....do you get where I'm coming from? We do this for fun, not to prove a point or one up one another. I'd love for you to continue to hang here and participate, seriously.

inspiredsports

OK, I can't figure out in which of the 17 inductor threads I offered this, but the question was if 15 turns unwound from an Erse Super Q 17mH 16AWG would bring it down to agout 16mH. I offered to contact Erse because I have a dialogue going with them on my project.

So based upon the email below, if you choose the 16AWG Erse Super Q route, pay $10 and have Erse send you a perfect (well, 5% tolerance) 16mH 16AWG inductor.

################################################################

---

Original Message

---

From: Jim Smolik [mailto:jim.smolik@erseaudio.com]
Sent: Friday, October 21, 2011 3:25 PM
To: help@bike-run-walk.com; 'Sales ERSE Audio'
Subject: RE: Another Super Q question

Not an exact science, depends upon the laminated core as they are not all exactly the same.

15 turns is about right, but once again not an exact science. We can unwind them here and make them exact for $10 per coil.

Hope that helps.

Thanks,
Jim Smolik
ERSE Audio
PH : 440-205-9658
FAX: 440-205-9659
email: jim.smolik@erse.cc
website : www.erseaudio.com
#######################################################


NOTE: They can't do this (unwind) in their heavier gauge 14AWG Super Q as they stop at 15mH. They need a 50 pc. minimum special order to produce 16mH in 14AWG.

Toolfan66

Way to go Greg!!! Thats good info!!

evhudsons

Great info!

Anyone to chime in here? I'm holding off on my inductors until I get more feedback after the burn in time. I wondering if the optimal number of unwinds etc may depend on the burn in time factor.

OldmanSRS

dorokusai wrote: »

Oh by all means, your years of R&D make up for an absurd suggestion when it comes to unwinding inductors? Who cares? Your experience in the application you tried cannot be argued as it's your observation but suggesting that folks start (un)rolling their own is weird. Can you find that advice elsewhere?

---

Original Message

---

From: Jim Smolik [mailto:jim.smolik@erseaudio.com]
Sent: Friday, October 21, 2011 3:25 PM
To: help@bike-run-walk.com; 'Sales ERSE Audio'
Subject: RE: Another Super Q question

Not an exact science, depends upon the laminated core as they are not all exactly the same.

15 turns is about right, but once again not an exact science. We can unwind them here and make them exact for $10 per coil.

Hope that helps.

Thanks,
Jim Smolik
ERSE Audio
PH : 440-205-9658
FAX: 440-205-9659
email: jim.smolik@erse.cc
website : www.erseaudio.com


So we have the answer. Do it my way and take 15 turns off yourself or send it to the wierd and absurd people at Erse and let them unwind it for you for $10 within a +/-5% tolerance = 16.8 mH to 15.2 mH.

inspiredsports

evhudsons wrote: »

Great info!

Anyone to chime in here? I'm holding off on my inductors until I get more feedback after the burn in time. I wondering if the optimal number of unwinds etc may depend on the burn in time factor.

Interestingly, Erse wrote (in a prior email to OldManSRS when he was performing his 1.2TL mod) that burn-in is not necessary. Other manufacturers (and other Polkies) report burn-in is a must.

HOWEVER, I believe the question was answered by Erse more from more of a, "does the inductance change with burn-in?" perspective.

DK has exposed that it is not an inductance issue, but what I will loosely call a "skin effect" issue wherein the insulation and conductive components need time to settle in.

Based upon what I've read here, consensus would be to not consider doing any critical listening or to make any changes based upon what you hear prior to approximately 150 hours of an amplified music-style signal running through the inductor.

Iron cores may be less affected as they use fewer feet of wire per mH, but I'm going to be patient nonetheless.


(Remember, there are 2 main aspects of this argument; the raw inductance value and the amount of distortion within the component.)

Joe08867

Good to know they will do it for you for a nominal fee. Seems the best way to go IMHO...

heiney9

Joe08867 wrote: »

Good to know they will do it for you for a nominal fee. Seems the best way to go IMHO...

Yes, because I'm sure they measure it as well.

inspiredsports

Edited:

I want to make sure I'm being exact. Erse states, "Tolerance: +/- 5% centered on nominal value"

They also say they can make coils to 1% tolerence. I'm guessing when they custom wind they are closer than 5%.

OldmanSRS

Install your 5% or 1% tolerance Erse inductors. If the bass sounds thin like I experienced, then what?